The formation of platelet thrombi is a normal component of the hemostatic response to lesions that cause bleeding. In pathological conditions, platelet thrombi may form at sites of vascular injury and cause arterial occlusion with interruption of blood flow to vital organs. The study of the mechanisms of platelet function is essential to find new therapeutic modes of intervention to prevent or cure the consequences of arterial thrombosis. We are studying the effect of diabetes mellitus (IDDM) on platelet alterations and thrombus formation. In IDDM, platelet thrombi may develop due to platelets abnormal hyperactivity and in response to alteration in the vessel wall. The result of this abnormal process is vascular occlusion and consequent tissue damage. To analyze this pathological process in IDDM, blood from patients will be passed in a perfusion chamber under relevant flow conditions over different matrix components.